Immunology and Inflammation Flashcards
What cells are activated during an innate immune response?
‘First response’
Granulocytes (bac-neutrophils, parasites-eiosinophils, basophils)
Mast cells
APCs
What two types of cells are commonly APCs?
Macrophages
Dendritic cells
How do APCs come to have antigens to be presented?
Phagocytose bacterium and parasites, through digestion antigens are produced and displayed on cell surface
CD4+ cells are also known as _______ and more specific to _______.
T helper cells
bacteria
(displayed along with MHC II protein)
CD8+ cells are also known as _______ and more specific to _______.
Cytotoxic T cells (nucleated)
viruses
(displayed along with MHC I protein, like all other nucleated cells in the body)
Activation of the adaptive immune system means involvement of what two cells?
T and B cells
What does humoral immunity involve?
Activation of B cells and Ab’s
What cells do cellular immunity involve and what do each do?
T helper cells (CD4+)- ‘effector cells’ regulate cytokines, B cells
Cytotoxic T cells ( CD8+)- mediates cell lysis/death
What two processes are Eicosanoids involved in?
Inflammation
Cellular signaling
What Eicosanoids arise from the lipooxygenase pathway?
Leukotrienes
What Eicosanoids arise from the cyclooxygenase pathway?
Prostaglandins
Prostacyclins
Thromboxanes
What is a common precursor to eicosanoids and via what two pathways can it be metabolized?
Arachidonic Acid
Lipooxygenase pathway and the Cyclooxygenase pathway
Explain how A.A. is broken down via the cyclooxygenase pathway.
A.A. is broken down by COX-1 and COX-2 which can lead to vasodilation, vasoconstriction, platelet inhibition and aggregation, fever, and bronchoconstriction
What are the two most common drugs used to inhibit the cyclooxygenase pathway?
NSAIDs
COX-2 inhibitors
What drugs can inhibit A.A. production and how?
Glucocorticoids (steroids) by inhibiting phospholipase A2, a precursor to A.A
Explain how A.A. is broken down via the lipooxygenase pathway.
A.A. is broken down by 5-lipooxygenase which can lead to:
Mast cells, basophils, and eosinophils (bronchoconstriction, vasoconstriction, dec. cor. blood flow, decrease cardiac contractility, etc)
OR
Neutrophils
(activation=migration, degranulation, eicosanoid synthesis, etc)
What drug can inhibit the 5-lipooxygenase, therefore inhibiting the lipooxygenase pathway?
Zileuton (FLAP inhbitors)
What is the pathophysiology of an allergic reaction?
An allergen stimulates the immune response. APCs engulf allergen and display on cells surface, activating T helper cells. T helpers cells recruit B cells to produce IgE specific to the allergen. IgE causes degranulation of mast cells and basophils which leads to the release of histamine and other inflammatory mediators
Local histamine vs systemic histamine release:
Local: erythema, edema, itching
Systemic: vasodilation, hypotension, bronchoconstriction
Where is histamine synthesized?
Mast cells and basophils (Inflam mediator)
Gastric mucosal cells (Regulates gastric acid secretion)
Neurons in the CNS (Regulates neurotransmission)
Where are H1 receptors found?
Smooth muscle, vascular endothelium, brain
What is H1's effect on: Lungs: Vascular sm. muscle: Vascular endothelium: Peripheral nerves:
Lungs: bronchoconstriction (asthma)
Vasc. sm. muscle: postcapillary venule dilation (erythema)
Vasc. endothelium: cellular contraction (edema)
Peripheral nerves: sensitization (itching, pain)
Where are H2 receptors found?
Gastric parietal cells, cardiac muscles, mast cells, braine
What are H2’s effect on:
Heart:
Stomach:
Heart: minor increase in HR and contractility
Stomach: gastric acid secretion (PUD, GERD)
H1 antihistamines are inverse agonists because they ______________ .
Cause the H1 rc to be inactivated, stabilizing it.
H1 rc is in active state at baseline, H1 antihistamines cause the rc to be inactivated.
What type of rc are histamine rc’s?
seven-transmembrane G protein-coupled receptors
How are H1 antihistamines metabolized?
CYP 450
How well are H1 antihistamines absorbed and when do they reach their Cmax?
Very well absorbed.
Cmax 2-3hrs
Describe first generation H1 antihistamines:
Lipophilic
Neutral at physiologic pH
Easily cross BBB
Work faster
What are examples of first generation H1 antihistamines?
Diphenhydramine Hydroxyzine Chlorpheniramine Promethazine Doxepin
Describe second generation H1 antihistamines:
Highly albumin bound Ionized at physiologic pH Does not cross BBB Stay in pl. longer (dec. SE) Hepatically metabolized Work slower
What are examples of second generation H1 antihistamines?
Loratidine Desloratidine Cetirizine Levocetirizine Fexofenadine
What are H1 antihistamines most commonly used for?
Rhinitis, conjunctivitis, urticaria, pruritis
Are H1 antihistamines effective for systemic anaphylaxis or asthma?
No, antihistamines only affect histamine rc not local mediators.
First generation H1 antihistamines can also be used to treat:
Motion sickness, chemotherapy related n/v: diphenhydramine, dimenhydrinate, meclizine, promethazine
Insomnia: diphenhydramine, doxylamine (indicated for sleep)
How do diphenhydramine, dimenhydrinate, meclizine, and promethazine decrease motion sickness and chemo related n/v?
Inhibits histamine signals from the vestibular nucleus which is the control center for vomiting in the medulla
AE of H1 antihistamines include:
Sedation Cardiac toxicity (QT prolongation, d/t CYP 3A4 interactions) Anticholinergic effects (pup. dilatation, dry eyes, dry mouth, urinary hesitancy)
How do sympathetic and parasympathetic tone affect the airway and at what receptors?
Sympathetic: Bronchodilation at the B2 rc
Parasympathetic: Bronchoconstriction at the muscarinic rc
The 3 main types of bronchodilators are:
B-agonists
Anticholinergics
Methylxanthines
Why are drugs such as terbutaline, albuterol, and levalbuterol more commonly used as bronchodilators in asthmatics?
They have more selectivity for B2 agonists. (sympathetic NS)
Epi for example is non selective and isoproterenol and metaproterenol affect B1 and B2 rc’s (could cause cardiac stim)
What is the onset, peak, and duration of action of B-agonists and how does that lend to their use?
Onset: 15-30mins
Peak: 30-60mins
Duration: 4-6 hrs
They are used as rescue inhalers and dose according to duration of action (poor ON control)
When would B-agonists be used prophylactically?
Prior to a known trigger (ex-exercise)